A group of men, predominantly Irish and mostly Catholic, fought under the banner of St. Patrick on the losing side of the Mexican-American War. Their journey from the Emerald Isle to the New World was one prompted by famine and death, and their arrival could not have been more poorly timed. America was racked by forces of divisiveness and turmoil: immigrants fed the nativist prejudices and anti-Catholic sentiments, slave states self-righteously fought off the incursions of abolitionists, while expansionists thought the problems of the U.S. could be solved by westward settlement. To the west and south was Mexico, a relatively new and unstable republic, promising both a pressure valve for immigration and room for growth.
There were the grasslands of Texas, the valuable ports of San Francisco and San Diego, the rich valleys of California, and untold mineral wealth.
Mexico, a land whose northern borders touched the plains of Kansas and the peaks of Colorado, was attractive indeed.
Some of the Irish, encountering prejudice in the States, headed to this Mexican territory. Mexico, a Catholic country, readily welcomed settlers from Ireland. Other Irishmen, unable to find employment in the North, joined the American Army. They, too, would head into Mexican territory, less willing perhaps but no less significantly, as part of the Army of Occupation. Some of them would desert and join their compatriots already fighting on the Mexican side when the Americans invaded. For most of them their end would be bloody and cruel. The fortunate ones died in battle. Others who survived to be captured by the American forces were brutally whipped and branded. Forty-eight of them were executed in what has been described as the "largest hanging affair on the North American continent." They are known in Mexico quite simply as the "Irish Catholic martyrs." In the U.S. when mentioned at all, they are simply called "turncoats" and "traitors."
Most histories of war are written by the victors who, by the very fact that they have won, are prone to discount atrocities committed by their side, minimize their opportunistic or selfish motives in waging the war, and denigrate the qualities of the losing side. The "War of Intervention" (1846-47), as it is known in Mexico, is no exception to this rule. The fact that the war is called the "Mexican-American War" in the United States presents the initial controversy. Did the United States invade its southern neighbor? Most U.S. historians, while reluctantly acknowledging that it did, argue that nevertheless Mexico shed the first blood and, therefore, was the aggressor.
Sources:
1. National Archives, Record Group 84, Miscellaneous Papers, Box 7, Office of the Adjutant General, Letter of Philip O'Brien, October 25, 1895.
2. Milton Meltzer, Bound For The Rio Grande. The Mexican Struggle 1845.1850, P. 205.